Method of running a tubing hanger and internal tree cap simultaneously

ABSTRACT

An assembly for the completion of a subsea horizontal tree that includes a tubing hanger, an internal tree cap, and a running tool.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. utility patentapplication Ser. No. 11/690,373, attorney docket number V2006068, filedon Mar. 23, 2007, the disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates in general to subsea wellhead equipment, and inparticular to a method of simultaneously running an internal tree capand tubing hanger into a subsea horizontal treehead.

BACKGROUND OF THE INVENTION

A conventional subsea horizontal tree includes a wellhead housing whichcontains one or more casing hangers, one of which is secured to a stringof production casing that extends into the well. A horizontal tree body,also known as a tree or tubing spool or spool tree, mounts to the top ofthe wellhead housing and seals to it. The horizontal tree body has acentral bore axially through it and a horizontal or lateral productionflow passage through the wall of the horizontal tree body. A tubinghanger lands and seals in the central bore of the horizontal tree bodyand is secured to a string of tubing that extends through the productioncasing hanger and production casing into the well. The tubing hanger hasa production bore axially through it that is in fluid communication withthe tubing. The tubing hanger also has a lateral flow passage in fluidcommunication with the tubing hanger production bore and with thelateral production flow passage in the horizontal tree body.

Annular seals are located between the tubing hanger and the central boreof the horizontal tree body above the production flow passage to provideprimary, and occasionally, secondary barriers to leakage from theproduction flow pathways and well bore. Additionally, one or morewireline deployable plugs fit in one or more lockdown profiles in thetubing hanger production bore to provide primary, and occasionally,secondary barriers to leakage from the production and well bores. A treecap may also fit above the tubing hanger in the central bore of thehorizontal tree body. The tree cap may be of an internal or externallockdown configuration. In either case, the tree cap will seal to thecentral bore of the horizontal tree body and act as an additionalbarrier to leakage from the well. The tree cap of either configurationmay have a vertical bore through it.

Another typical feature of subsea horizontal trees is an annulus andworkover passageway that establishes a fluid communication pathwaybetween the annular space around the tubing below the tubing hanger anda space inside the central bore of the horizontal tree body above thetubing hanger. This annulus and workover passageway can be portedthrough the tubing hanger, through the horizontal tree body or acombination of both. Alternatively, the annulus and workover passagewaymay be ported entirely out of the tree from a position below the tubinghanger.

In practice, there are generally two horizontal tree configurations: (1)a horizontal tree with a tubing hanger fitted with one or more plugs inits production bore and an internal tree cap, with a plug in itsvertical bore; or (2) a horizontal tree with a tubing hanger fitted withat least two plugs in its production bore and eliminating the internaltree cap. This second style of horizontal tree typically utilizes a treecap that locks externally to the tree body and may or may not include aseal to the tree body. In either tree cap case, the annulus and workoverpassageway will contain at least two closure members in the form of gatevalves, for example.

The primary difference between these two general horizontal treeconfigurations is that the first has a primary and secondary barrierthat employs independent lockdown structures for the two barriers, andthe second has a primary and secondary barrier that ultimately rely onthe tubing hanger to horizontal tree body lockdown structure. Someoperators, and some regulatory authorities believe that the first andsecond horizontal tree configurations are equivalently safe inoperation. Other operators and regulatory authorities believe only thefirst configuration meets the dual barrier industry philosophies and/orregulatory requirements.

One advantage of the second configuration is that the elimination of theinternal tree cap eliminates the need for a second drill pipe run toinstall it. In running (or working over) the first style of horizontaltree, the tubing hanger is run into the horizontal tree body typicallyon a hydraulically-actuated running tool that is run on drill pipe.Afterwards, the internal tree cap is run into the horizontal tree bodytypically on the same hydraulically-actuated running tool, or one verysimilar, on drill pipe. This results in two drill pipe trips to theseafloor.

In running (or working over) the second style of horizontal tree, thetubing hanger is run into the horizontal tree body typically on thehydraulically-actuated running tool on drill pipe. Afterwards, a lowerplug is run on wireline and landed, locked and sealed to the productionbore of the tubing hanger and then an upper plug is run on wireline andlanded, locked and sealed to the production bore above the first plug.In deeper water wells, this results in potentially significant rig timesavings. However, it comes with the compromise that the two plugs relyon the single tubing hanger lockdown mechanism to ensure that the tubingstring assembly does not part from the tree and cause potentiallysignificant leakage of the well bore to the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary cross sectional illustration of an exemplaryembodiment of a tubing hanger and internal tree cap assembly.

FIG. 2 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 1 during assembly.

FIG. 3 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 2 during further assembly.

FIG. 4 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 3 during placement of theassembly within an end of a treehead.

FIG. 5 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 4 during operation of theassembly to connect the tubing hanger to the treehead.

FIG. 6 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 5 during operation of theassembly to connect the internal tree cap to the treehead.

FIG. 7 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 6 during operation of theassembly to unlock the running tool from the internal tree cap.

FIG. 8 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 7 during operation of theassembly to remove the running tool from the treehead.

FIG. 9 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 8 during operation of theassembly to position crown plugs within the internal tree cap and thetubing hanger.

FIG. 10 is a fragmentary cross sectional illustration of the tubinghanger and internal tree cap assembly of FIG. 9 during operation of theassembly to remove the crown plugs and the internal tree cap from thetreehead.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings and description that follows, like parts are markedthroughout the specification and drawings with the same referencenumerals, respectively. The drawings are not necessarily to scale.Certain features of the invention may be shown exaggerated in scale orin somewhat schematic form and some details of conventional elements maynot be shown in the interest of clarity and conciseness. The presentinvention is susceptible to embodiments of different forms. Specificembodiments are described in detail and are shown in the drawings, withthe understanding that the present disclosure is to be considered anexemplification of the principles of the invention, and is not intendedto limit the invention to that illustrated and described herein. It isto be fully recognized that the different teachings of the embodimentsdiscussed below may be employed separately or in any suitablecombination to produce desired results. The various characteristicsmentioned above, as well as other features and characteristics describedin more detail below, will be readily apparent to those skilled in theart upon reading the following detailed description of the embodiments,and by referring to the accompanying drawings.

Referring to FIG. 1, a tubing hanger and internal tree cap assembly 100includes a tubing hanger 102 that defines an internal passage 102 a anda radial passage 102 b and includes an internal annular recess 102 c, aninternal annular recess 102 d at one end, an external annular recess 102e, an external annular recess 102 f, an external annular recess 102 g,an external annular recess 102 h, an external annular recess 102 i, anexternal annular recess 102 j, and internal threaded portion 102 k atone end.

A tubular locking ring retainer 104 defines a window 104 a and includesa tapered external shoulder 104 b that mates with and is supported onthe annular external recess 102 e of the tubing hanger 102 and aninternal annular recess 104 c. A conventional split locking ring 106 isreceived within the window 104 a of the locking ring retainer 104 andincludes a profiled external surface 106 a and a tapered internalsurface 106 b. An end of a sleeve 108 is mates with and is supported onthe external annular recess 102 g of the tubing hanger 102 and anotherend of the sleeve mates with and is supported on the external annularrecess 102 h of the tubing hanger 102.

A tubing hanger support 110 defines a radial passage 110 a that isoperably coupled to the radial passage 102 b of the tubing hanger 102and includes an internal annular recess 110 b at one end that mates withan end of the sleeve 108, an internal flange 110 c that mates with andis received within the external annular recess 102 h of the tubinghanger, an internal annular recess 110 d that mates with the externalannular recess 102 i of the tubing hanger, an internal flange 110 e thatmates with and is received within the external annular recess 102 i ofthe tubing hanger, an external flange 110 f, an external annular recess110 g, and an internal profiled annular recess 110 h. An energizing ring112 includes a tapered external annular recess 112 a at one end,internal grooves 112 b at one end, an internal annular recess 112 c thatmates with an receives a portion of the tubing hanger support 110, aninternal annular recess 112 d that mates with and receives the externalflange 110 f of the tubing hanger support, a tapered internal annularrecess 112 e, and an internal annular recess 112 f.

A lower end of a tubular support member 114 is positioned in opposingrelation to an upper end of the tubing hanger support 110 and includesan internal annular recess 114 a, an external annular recess 114 b, anexternal threaded portion 114 c at an upper end, and an externalthreaded portion 114 d at the upper end. A tubular support member 116includes a tapered internal annular recess 116 a at one end, an internalthreaded portion 116 b at another end that engages the external threadedportion 114 c of the tubular support member 114, a tapered externalannular recess 116 c at the other end, an external annular recess 116 d,an external annular recess 116 e, and an external annular recess 116 fthat mates with an upper end of the energizing ring 112. A snap ring 118is at least partially received within the external annular recess 116 eof the tubular support member 116 and the internal annular recess 112 fof the energizing ring 112. In this manner, the snap ring 118 releasablyholds the upper end of the energizing ring 112 within the externalannular recess external annular recess 116 f of the tubular supportmember 116.

An upper end 120 a of a locking dog 120 is retained within the externalannular recess 114 b of the tubular support member 114 by the taperedinternal annular recess 116 a of the tubular support member 116 and alower end 120 b of the locking dog is retained within the externalannular recess 110 g of the tubing hanger support 110 by the energizingring 112. A tubular support 122 defines a window 122 a and includes aninternal threaded portion 122 b at one end that is coupled to anexternal threaded portion 102 k of the tubing hanger 102. An upper end124 a of a latch dog 124 is retained within the internal annular recess114 a of the tubular support member 114 by the upper portion of thetubular support 122 and a lower end 124 b of the latch dog mates withand is received within the internal annular recess 110 h of the tubinghanger support 110. In an exemplary embodiment, the locking dog 120 andthe latch dog 124, either alone or in combination, provide a linkingassembly for linking the internal tree cap 126 and the tubing hanger102. Furthermore, in an exemplary embodiment, as a result, the internaltree cap 126 supports the weight on the tubing hanger 102.

An internal tree cap 126 includes an external annular recess 126 a atone end, a channel 126 b at one end that receives and mates with theupper ends of the tubular support member 114 and the tubular supportmember 116, an internal tapered annular recess 126 c at one end thatmates with and receives an upper end of the tubular support 122, aninternal annular recess 126 d, an internal profiled annular recess 126e, an channel 126 e, an external annular recess 126 f, an externalannular recess 126 g, an external annular recess 126 h, an externalannular recess 126 i at another end, an internal annular recess 126 j atanother end, and an external tapered annular recess 126 k at a lowerend. A sleeve 128 includes an external ribbed surface 128 a at one end,an internal annular recess 128 b at one end, and another end that mateswith and is received within the external annular recess 126 h of theinternal tree cap 126. A tubular support member 130 includes an internalannular recess 130 a at one end that mates with and receives an upperend of the sleeve 128, an internal annular recess 130 b that mates withand is received within the external annular recess 126 h of the internaltree cap 126, another end that mates with and is received within theexternal annular recess 126 i of the internal tree cap 126, an externalannular recess 130 c, an external flange 130 d, and an external flange130 e that defines a longitudinal passage 130 f therethrough.

An energizing ring 132 that includes an internal profiled annular recess132 a, an internal annular recess 132 b that receives and mates with theexternal flange 130 e of the tubular support member 130, an internalannular recess 132 c that receives and mates with a lower end of thetubular support member 130, an external tapered external annular recess132 d at another end, and an internal ribbed surface 132 e at anotherend, mates with and receives the sleeve 128. A conventional splitlocking ring 134 is received within the external annular recesses, 126 fand 126 g, of the internal tree cap 126, and includes a profiledexternal surface 134 a and a tapered internal surface 134 b.

An upper tubular running tool 136 that defines a radial passage 136 a atone end and a longitudinal passage 136 b that depends therefrom andextends to another end, and includes a tapered external annular recess136 c and an internal annular recess 136 d at the other end is receivedwithin an mates with the internal tree cap 126. A lower tubular runningtool 138 that defines a longitudinal passage 138 a that is and a radialpassage 138 b that extends therefrom and includes a tapered externalflange 138 d that is received within and mates with the internal annularrecess 126 d of the internal tree cap 126, and an external annularrecess 138 e that receives and mates with the tubing hanger 102 includesan upper end that mates with and is received within a lower end of theupper tubular running tool 136. A tubular conduit 140 extends betweenand operably couples opposing ends of the passageways, 136 b and 138 a,of the upper and lower tubular running tools, 136 and 138, respectively.A tool finger 142 is pivotally coupled to an outer surface of the lowertubular running tool 138 proximate the external flange 138 d for pivotalmovement relative thereto.

Referring now to FIG. 2, in an exemplary embodiment, the upper tubularrunning tool 136 is then displaced in the direction of the lower tubularrunning tool 138. As a result, the external tapered annular recess 136 cof the upper tubular running tool 136 is displaced into engagement withthe tool finger 142 thereby pivoting the tool finger outwardly in aradial direction and into the profiled internal annular recess 126 e ofthe internal tree cap 126 thereby locking the internal tree cap to thelower tubular running tool 138. Furthermore, as a result, the internalannular recess 136 d of the upper tubular running tool is displaced intoengagement with the upper end of the lower tubular running tool 138thereby displacing the conduit 140 into the upper end of thelongitudinal passage 138 a of the lower tubular running tool.

Referring now to FIG. 3, in an exemplary embodiment, a universal runningtool 200 is then coupled to the assembly 100 that includes an innersleeve 202 that defines a longitudinal passage 202 a and a radialpassage 202 b that depends therefrom and includes an internal annularrecess 202 c at one end. At least a portion of an upper end of the uppertubular running tool 136 is received within and mates with a lowerportion of the inner sleeve 202. An inner sleeve 204 that defines aradial passage 204 a is received within and mates with the internalannular recess 202 c of the inner sleeve 202, receives and mates withthe upper tubular running tool 136, and is received within and mateswith the internal annular recess 126 j of the internal tree cap 126.

An internal sleeve 206 that defines an internal annular recess 206 areceives and mates with the inner sleeve 202 and is received within andmates with the internal annular recess 132 b of the energizing ring 132.An internal sleeve 208 is received within and mates with the internalannular recess 206 a of the internal sleeve. An internal sleeve 210 iscoupled to an end of the inner sleeve 202 and positioned within theannular recess 206 a of the internal sleeve 206 and an end of theinternal sleeve 210 is received within and mates with the externalannular recess 130 c of the tubular support member 130. An outer sleeve212 that defines an internal annular recess 212 a and an internalannular recess 212 b receives and mates with the inner sleeve 206. Anupper end 214 a of a latch 214 is received within the internal annularrecess 212 a of the outer sleeve 212 and a lower end 214 b of the latchis received within the internal annular recess 132 a of the energizingring 132.

An upper end 216 a of a locking sleeve 216 is received within and mateswith the internal annular recess 206 a of the inner sleeve 206 and ispositioned proximate a lower end of the internal sleeve 208 and above atleast a portion of the internal sleeve 210 and a lower end 216 b of thelocking sleeve 216 is received within and mates with the internalannular recess 206 a of the inner sleeve 206 and is positioned below atleast a portion of the internal sleeve 210. In this manner, theuniversal running tool 200 is locked to the internal tree cap 126.

Referring now to FIG. 4, in an exemplary embodiment, the coupledassemblies, 100 and 200, are then run into an open end of a conventionaltreehead 300 that includes an upper profiled internal annular recess302, an internal load shoulder 304, a lower profiled internal annularrecess 306, and an internal load shoulder 308. In particular, thecoupled assemblies, 100 and 200, are then run into an open end of thetreehead 300 until the external tapered annular recess 126 k of theinternal tree cap 126 lands on the internal load shoulder 304 of thetreehead 300 and the tapered external shoulder 104 b of the locking ringretainer 104 lands on the internal load should 308 of the treehead.

Referring now to FIG. 5, in an exemplary embodiment, a pump 400 is thenoperated to inject a fluidic material into and through the passage 202 aof the sleeve 200. As a result, fluidic material is then conveyed intoand through the passages, 204 a, 136 a, 136 b, the conduit 140, and thepassages 138 a, 138 b, 102 b, and 110 g. As a result, the energizingring 112 is displaced downwardly into engagement with the locking ring106. As a result, the interaction of the tapered external annular recess112 a of the energizing ring 112 with the tapered internal surface 106 bof the locking ring 106 causes the locking ring to be displacedoutwardly in a radial direction into engagement with the profiledinternal recess 306 of the treehead 300.

Furthermore, the downward displacement of the energizing ring 112 alsomoves the energizing ring out of engagement with the lower end 120 b ofthe a locking dog 120. As a result, the lower end 120 b of the lockingdog 120 may pivot outwardly out of engagement with the external annularrecess 110 g of the tubing hanger support 110.

Referring now to FIG. 6, in an exemplary embodiment, the outer sleeve ofthe assembly 200 is displaced downwardly thereby causing the energizingring 132 to be displaced downwardly. As a result, the interaction of thetapered external annular recess 132 d of the energizing ring 132 withthe tapered internal surface 134 b of the locking ring 134 causes thelocking ring to be displaced outwardly in a radial direction intoengagement with the profiled internal recess 302 of the treehead 300thereby locking the internal tree cap 126 to the treehead 300. In anexemplary embodiment, as a result, the internal tree cap 126 then atleast partially supports the weight of the tubing hanger 102 and theupper and lower tubular running tools, 136 and 138.

Referring now to FIG. 7, in an exemplary embodiment, the upper tubularrunning tool 136 is then displaced upwardly relative to the lowertubular running tool 138. As a result, the external tapered annularrecess 136 c of the upper tubular running tool 136 is moved out ofengagement with the tool finger 142. As a result, the tool finger 142may pivot out of engagement with the internal annular recess 126 e ofthe internal tree cap 126 thereby unlocking the internal tree cap fromthe lower tubular running tool 138.

Referring now to FIG. 8, in an exemplary embodiment, the upper and lowertubular running tools, 136 and 138, are then removed. As a result, thelower end 124 b of the latch dog 124 may pivot out engagement with theinternal annular recess 110 h of the tubing hanger support 110.

Referring now to FIG. 9, in an exemplary embodiment, conventional crownplugs, 500 a and 500 b, may then be coupled to the profiled internalannular recesses, 126 e and 102 c, of the internal tree cap 126 and thetubing hanger 102, respectively, in a conventional manner.

Referring now to FIG. 10, in an exemplary embodiment, the crown plugs,500 a and 500 b, may then be decoupled from the profiled internalannular recesses, 126 e and 102 c, of the internal tree cap 126 and thetubing hanger 102, respectively, in a conventional manner. In anexemplary embodiment, the energizing ring 132 may then be displacedupwardly relative to the locking ring 134 thereby decoupling the lockingring from the profiled inner annular recess 302 of the treehead 300. Asa result, the internal tree cap 126 is no longer locked to the treehead300. In an exemplary embodiment, the assembly 200 may then be displacedupwardly relative to the treehead 300. As a result, the tubular supportmember 114, the tubular support member 116, the locking dog 120, thetubular support 122, the latch dog 124, the internal tree cap 126, thesleeve 128, the tubular support member 130, the energizing ring 132, andthe locking ring 134 are also displaced upwardly out of the treehead 300and out of engagement with the tubing hanger 102.

It is understood that variations may be made in the above withoutdeparting from the scope of the invention. For example, the teachings ofthe exemplary embodiments may also be used to complete a wellhead,treehead, or other equivalent structure. While specific embodiments havebeen shown and described, modifications can be made by one skilled inthe art without departing from the spirit or teaching of this invention.The embodiments as described are exemplary only and are not limiting.Many variations and modifications are possible and are within the scopeof the invention. Accordingly, the scope of protection is not limited tothe embodiments described, but is only limited by the claims thatfollow, the scope of which shall include all equivalents of the subjectmatter of the claims.

1. A method of completing a well comprising a treehead comprising abore, comprising: (a) connecting a running tool to an internal tree capand to a tubing hanger, then lowering the internal tree cap and tubinghanger as an assembly, and landing the tubing hanger in the bore of thetreehead; then (b) locking the tubing hanger to the bore of the treeheadby injecting fluidic material into and through the running tool and thetubing hanger; and then (c) locking the internal tree cap to the bore ofthe treehead.
 2. The method of claim 1, wherein (a) comprises:connecting a lifting device of the running tool to the internal tree capand connecting a linking assembly between the internal tree cap and thetubing hanger so that the internal tree cap supports the weight of thetubing hanger through the linking assembly.
 3. The method of claim 2,wherein (a) comprises: connecting a pivoting linking assembly betweenthe internal tree cap and the tubing hanger so that the internal treecap supports the weight of the tubing hanger through the linkingassembly.
 4. The method of claim 3, wherein (a) comprises: connectinginternal and external pivoting linking assemblies between the internaltree cap and the tubing hanger so that the internal tree cap supportsthe weight of the tubing hanger through the linking assembly.
 5. Themethod of claim 2, wherein (a) comprises: locking the lifting device ofthe running tool to an internal recess defined in the internal tree cap.6. The method of claim 1, wherein the tubing hanger comprises a radiallymovable locking element and an axially movable actuator; and wherein (b)comprises stroking the actuator of the tubing hanger to cause thelocking element of the tubing hanger to move radially into a lowerprofile formed in the bore of the treehead.
 7. The method of claim 1,wherein the internal tree cap comprises a radially movable lockingelement and an axially movable actuator; and wherein (c) comprisesstroking the actuator of the internal tree cap to cause the lockingelement of the internal tree cap to move radially into an upper profileformed in the bore of the treehead.
 8. The method of claim 1, whereinthe internal tree cap and the tubing hanger each comprise a radiallymovable locking element and an axially movable actuator; wherein (b)comprises stroking the actuator of the tubing hanger to cause thelocking element of the tubing hanger to move radially into a lowerprofile formed in the bore of the treehead; and wherein (c) comprisesstroking the actuator of the internal tree cap to cause the lockingelement of the internal tree cap to move radially into an upper profileformed in the bore of the treehead.
 9. The method of claim 1, whereinthe running tool comprises a longitudinal passage; and wherein thetubing hanger comprises a radial passage coupled thereto.
 10. The methodof claim 1, further comprising, after (c), retrieving the running tool.11. The method of claim 1, further comprising, after (c), retrieving theinternal tree cap and the linking assembly.
 12. A well assembly,comprising: a treehead comprising a bore comprising upper and lowerprofiles; a tubing hanger defining a radial passage and comprising aradially movable locking element and an axially movable actuator formoving the locking element of the tubing hanger into engagement with thelower profile; an internal tree cap having a radially movable lockingelement and an axially movable actuator for moving the locking elementof the internal tree cap into engagement with the upper profile; alinking assembly for coupling the tubing hanger and the internal treecap; and a running tool defining a longitudinal passage operably coupledto the radial passage of the tubing hanger comprising a lift member thatreleasably engages a portion of the internal tree cap for lowering thetree cap into the bore of the treehead, and an actuator sleeve thatreleasably engages the actuator of the internal tree cap to stroke theactuator of the internal tree cap.
 13. The assembly of claim 12, whereinthe actuator of the tubing hanger is moved axially by fluidic pressure.14. The assembly of claim 12, wherein the linking assembly engagesprofiles formed in the tubing hanger and the internal tree cap.
 15. Theassembly of claim 12, wherein the linking assembly comprises: aninternal linking assembly; and an external linking assembly.
 16. Theassembly of claim 12, wherein the linking assembly is pivotally coupledto the internal tree cap.
 17. The assembly of claim 12, wherein the liftmember is pivotally coupled to the running tool.
 18. The assembly ofclaim 12, wherein the internal tree cap supports substantially all ofthe weight of the tubing hanger.
 19. An assembly for completing atreehead that comprises a bore comprising upper and lower profiles,comprising: a tubing hanger defining a radial passage and comprising aradially movable locking element and an axially movable actuator formoving the locking element of the tubing hanger into engagement with thelower profile of the treehead; an internal tree cap having a radiallymovable locking element and an axially movable actuator for moving thelocking element of the internal tree cap into engagement with the upperprofile of the treehead; and a linking assembly for coupling the tubinghanger and the internal tree cap.